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March 3rd, 2010, 12:57 PM   #1
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Is this possible?

Hi all.

Is it possible to find the point [x,y] if I know all the other variables on this diagram ([a,b], [c,d], length 1, length 2 and length 3)...


It's been quite a long time since I studied Maths so any help would be massively appreciated. It's to solve some Javascript code in some animation in case you're interested or if it helps to find a solution.

Thanks,
JimJam
http://www.jimjamgraphics.com/
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March 3rd, 2010, 03:13 PM   #2
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Re: Is this possible?

Quote:
Originally Posted by JimJamGraphics
Is it possible to find the point [x,y] if I know all the other variables on this diagram ([a,b], [c,d], length 1, length 2 and length 3)...
Yes; it's just a bit messy. A little old fashioned technique helps, but it's still messy, so far as I can see, with a quadratic holding a number of literal constants [l1, l2 etc.]
l3 is redundant, as it is determined by the given coordinates.

Neat way to throw in a bit of advertising by the way.
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March 4th, 2010, 08:29 AM   #3
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It's length 1 that is redundant. The point (x, y) could lie on either side of the line joining the given points, so a little extra information is needed to reduce the two possibilities to just one.
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March 4th, 2010, 09:14 AM   #4
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Re:

Quote:
Originally Posted by skipjack
It's length 1 that is redundant. The point (x, y) could lie on either side of the line joining the given points, so a little extra information is needed to reduce the two possibilities to just one.
Yes, that is the one I meant, obviously. I really should have taken typing more seriously. In any event, the point is that it is possible, but messy, and so needs only someone to spend the time.
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March 4th, 2010, 10:07 AM   #5
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Re: Is this possible?

Hello, JimJam!

Quote:
Is it possible to find the point [x,y] if I know all the other variables on this diagram
([a,b], [c,d], length 1, length 2 and length 3)

You should redraw the diagram . . . The point are collinear.


Code:
    (a,b)   (c,d)           (x,y)
      *-------*---------------*
      : - 1 - : - - - 2 - - - :
      : - - - - - 3 - - - - - :



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March 4th, 2010, 04:56 PM   #6
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That interpretation may be too literal. I interpreted "length 1" as meaning "variable 1", etc., so that the three lengths are given by three variables.
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